LED packaging structure

ABSTRACT

A light emitting diode packaging structure includes a package body, a red LED chip, a blue LED chip, a green LED chip, a package material and a yellow phosphor. Three LED chips are disposed within an accommodating room of the body package and covered by the package material. The yellow phosphor is uniformly mixed with the package material. A white light is formed by a mix of three types of light from the LED chips. Additionally, a yellow light which is generated from the excitement of the yellow phosphor with the blue light is mixed with a part of the blue light to further form the white light.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number95126989, filed Jul. 24, 2006, which is herein incorporated byreference.

FIELD OF THE INVENTION

The present invention generally relates to a light emitting diodepackaging structure. More particularly, this invention relates to alight emitting diode packaging structure to improve the color renderingproperty thereof.

BACKGROUND OF THE INVENTION

Semiconductor light emitting diode (LED) has become a promising devicefor general-purpose illumination applications. LEDs features include,excellent durability, long operation life, low power consumption,containing no mercury and potentially high efficiency. White LED is anillumination light source that is good for environmental protection andenergy saving. Recently, LEDs are progressively being used in theillumination field for the electronic devices. For example, LEDs arepopularly used in the mobile phones, personal digital assistants (PDAs)and so on.

Currently, the white LED adopts a red LED chip, a green LED chip and ablue LED chip to pack together in a packing structure so as to mix thethree colors to form the white light.

Additionally, the color rendering index (Ra) is a measure of the abilityof a light source to reproduce the colors of various objects being litby the source. A high color rendering index light source can provide abetter color representation for the object, that is, close to thenatural color thereof. However, the color rendering index of aconventional LED is very poor. For example, the color rendering index ofthe conventional LED with red, blue and green LED chips is about 60˜70.Therefore, there is a need to improve the color rendering index for theLED illumination device.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a light emitting diodepackaging structure to improve the color rendering index for the lightemitting diode with three fundamental color chips.

Another object of the present invention is to provide a light emittingdiode packaging structure, by simple packing processes, to improve thecolor rendering index of the light emitting diode.

Further, another object of the present invention is to provide a lightemitting diode packaging structure to reduce the driving current for thegreen LED chip to further uniform the driving currents of the threefundamental color LED chips.

To achieve these and other advantages and in accordance with the purposeof the present invention, as the embodiment broadly describes herein,the present invention provides a light emitting diode (LED) packagingstructure. The LED packaging structure includes a package body having anaccommodating room, an LED chipset, a package material, and a phosphormixed in the packing material. The LED chipset is disposed in theaccommodating room and includes a first LED chip to generate a greenlight having a wavelength about 510 nm to 550 nm, a second LED chip togenerate a blue light having a wavelength about 440 nm to 480 nm, and athird LED chip to generate a red light having a wavelength about 600 nmto 630 nm.

The package material is filled in the accommodating room to protect theLED chipset. Additionally, phosphor powder is mixed with the packingmaterial and able to generate a light with a wavelength about 560 nm to600 nm.

When the driving current is supplied through the electrode leads to theLED chips, a part of the blue light can excite the phosphor to generatea yellow light to mix with the blue light to form an additional whitelight while the green light, the blue light and the red light are mixedto form the white light.

Accordingly, the illumination device with the LED packaging structureaccording to the present invention can effectively improve the colorrendering index and the luminous efficiency thereof. Additionally, thedriving current of the LED chips are more consistent due to the reducedgreen light requirement and the increased blue light requirement.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will be more readily appreciated as the same becomes betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1A illustrates a top view of a preferred embodiment of the lightemitting diode packaging structure according to the present invention;

FIG. 1B illustrates a side view of the preferred embodiment of the lightemitting diode packaging structure of FIG. 1A; and

FIG. 2 illustrates another preferred embodiment of the light emittingdiode packaging structure according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is of the best presently contemplated mode ofcarrying out the present invention. This description is not to be takenin a limiting sense but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined by referencing the appended claims.

Referring to FIGS. 1A and 1B, a top view and a side view of a preferredembodiment of the light emitting diode packaging structure according tothe present invention are respectively illustrated. Additionally, thepackage material 104 is omitted from FIG. 1A to clearly present theaccommodating room 108.

In one embodiment, the light emitting diode packaging structure includesa package body 102, an LED chipset 110, a package material 104, aphosphor 106 and electrode leads.

The package body 102 is injected and formed by the materials ofpolyphthalamide (PPA), epoxy resin, glass fiber, calcium oxide and soon. The package body 102 includes an accommodating room 108 toaccommodate the LED chipset 110.

The LED chipset 110 includes a first LED chip 112, a second LED chip 116and a third LED chip 114. The first LED chip 112 can output a light withthe wavelength about 510 nm to 550 nm, for example, a green light LEDchip. The second LED chip 116 can output a light with the wavelengthabout 440 nm to 480 nm, for example, a blue light LED chip.Additionally, the third LED chip 114 can output a light with thewavelength about 600 nm to 630 nm, for example, a red light LED chip.

The package material 104 is filled in the accommodating room 108 tocover and protect the LED chipset 110 and allows the light emittingtherefrom. The package material 104 is, for example, epoxy resin,acrylic resin, silicone or the combination thereof.

The phosphor 106, for example, yellow phosphor, is uniformly mixed inthe package material 104 and emits the light with the spectrum ofradiation at about 560 nm to 600 nm peak wavelength while the phosphor106 is excited. Three fundamental LED chips can provide RGB lights tomix and form the white light. The second LED chip 116 can excite thephosphor 106 to emit an excited light which can mix with the blue lightgenerated by the second LED chip 116 to form a white light.

The electrode leads include the positive electrode leads 122 a, 124 a,126 a electrically connected to the positive electrodes of the LED chipsand the negative electrode leads 122 b, 124 b, 126 b electricallyconnected to the negative electrodes of the LED chips.

When the electrical power is supplied through the positive electrodeleads and the negative electrode leads to the corresponding LED chips,the LED chips generate corresponding lights. The blue light LED chip 116generates the blue light and a part of the blue light can excite theyellow phosphor 106 to emit yellow light so that another part of theblue light can mix with the yellow light to further form the additionalwhite light. The residual blue light is mixed with the green light andthe red light to form the white light.

In the embodiment, the three LED chips are triangularly arranged. Inother embodiments, the three LED chips can bein various arrangements.Referring to FIG. 2, another preferred embodiment of the light emittingdiode packaging structure according to the present invention isillustrated. The first LED chip 212, the third LED chip 214 and thesecond LED chip 216 are linearly arranged. Additionally, the second LEDchip 216 is disposed in the middle position to excite the phosphoreasily.

A yellow color light is excited to further mix into the white lightmixed by the fundamental color lights generated by the RGB LED chips soas to effectively improve the white light closer to the sunlight andincrease the color rendering index thereof. Additionally, the blue lightcan efficiently mix with the light with 560 nm to 600 nm wavelength toform the additional white light.

Additionally, the brightness ratio of a conventional RGB LED chipset inthe backlight module is about 3:6:1. Therefore, the driving current hasto over drive the green light LED chip to generate more green light.However, the driving current for the blue light LED chip has to downdrive the blue light LED chip to generate insufficient blue light.Therefore, the driving currents for the RGB LED chips are inconsistent.

The present invention adds the additional yellow phosphor in the packagematerial of the light emitting diode to spend the blue light so as tothe driving current for the blue LED chip is increased. Additionally,the blue light can mix with the yellow light to form additional whitelight so as to reduce the requirement of the green light and the drivingcurrent for the green LED chip. Accordingly, the driving currents forthe RGB LED chips are more consistent. The mixed ratio of the phosphorcan determine the final brightness of the LED and the purity of thewhite light so that a person skilled in the art can adjust the mixedratio of the phosphor according to the actual requirement of the LEDwithout departing from the scope and spirit of the present invention.

Compared with the conventional RGB LED illumination device, the presentinvention can improve the color rendering index for an illuminationdevice, for example, a backlight module, with the LED packagingstructure according to the present invention to represent actual colorson the object. The luminous efficiency of the illumination device canalso be improved since that the blue light and the yellow light can mixto form the additional white light.

The LED packaging structure, according to the present invention, has noadditional equipment requirement. There is only mixing the packagematerial with phosphor, able to generate 560 nm to 600 nm light, andmolding the LED chips in the accommodating room with the packagematerial mixing with the phosphor. Additionally, the blue light caneffectively mix with the yellow light to form the white light in a hightransformation efficiency. Furthermore, the driving currents of the RGBLED chips are more consistent.

As is understood by a person skilled in the art, the foregoing preferredembodiments of the present invention are illustrative of the presentinvention rather than limiting of the present invention. It is intendedthat various modifications and similar arrangements be included withinthe spirit and scope of the appended claims, the scope of which shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar structures.

1. A light emitting diode (LED) packaging structure, comprising: apackage body having an accommodating room; an LED chipset disposed inthe accommodating room, comprising: a first LED chip to generate a greenlight having a wavelength about 510 nm to 550 nm; a second LED chip togenerate a blue light having a wavelength about 440 nm to 480 nm; and athird LED chip to generate a red light having a wavelength about 600 nmto 630 nm; a package material disposed in the accommodating room toprotect the LED chipset; and a phosphor mixed in the packing materialand able to generate a light with a wavelength about 560 nm to 600 nm,wherein the green light, the blue light and the red light are mixed toform a white light, and the blue light further excites the phosphor togenerate the light with the wavelength about 560 nm to 600 nm for mixingwith the blue light to further form an additional white light.
 2. Thelight emitting diode (LED) packaging structure of claim 1, wherein thepackage material is epoxy resin, acrylic resin, silicone or acombination thereof.
 3. The light emitting diode (LED) packagingstructure of claim 1, wherein the first, second and third LED chips aretriangularly disposed in the accommodating room.
 4. The light emittingdiode (LED) packaging structure of claim 1, wherein the first, secondand third LED chips are linearly disposed in the accommodating room. 5.A light emitting diode (LED) packaging structure, comprising: a packagebody having an accommodating room; an LED chipset disposed in theaccommodating room, comprising: a first LED chip to generate a greenlight having a wavelength about 510 nm to 550 nm; a second LED chip togenerate a blue light having a wavelength about 440 nm to 480 nm; and athird LED chip to generate a red light having a wavelength about 600 nmto 630 nm; an electrode lead set having a plurality of positiveelectrode leads and a plurality of negative electrode leads toelectrically connect the first, second, and third LED chipsrespectively; a package material disposed in the accommodating room toprotect the LED chipset; and a phosphor mixed in the packing materialable to generate a light with a wavelength about 560 nm to 600 nm,wherein the green light, the blue light and the red light are mixed toform a white light, and the blue light further excites the phosphor togenerate the light with the wavelength about 560 nm to 600 nm for mixingwith the blue light to further form an additional white light.
 6. Thelight emitting diode (LED) packaging structure of claim 5, wherein thepackage material is epoxy resin, acrylic resin, silicone or thecombination thereof.
 7. The light emitting diode (LED) packagingstructure of claim 5, wherein the first, second and third LED chips aretriangularly disposed in the accommodating room.
 8. The light emittingdiode (LED) packaging structure of claim 5, wherein the first, secondand third LED chips are linearly disposed in the accommodating room.